First thing's first, safety! It was last plugged in and on about 20 hours ago. I'm assuming I need to discharge capacitors before working on this thing? What's the best way to go about this?

Anyway here's the problem. Channel A is a split channel, dirty/boost, and a footswitch activates the boost. The volume on this channel is practically non-existant. It's there if I turn everything up full, but not even loud enough to play along with some music. I haven't been able to try out the boost yet as I don't have a footswitch, but I'll let you know once I do.

There's no obvious soldering problems that I can see, but I haven't checked the underside of the boards, as I'm assuming it's not safe to. Here's a couple pictures of the front panel and the inside, if you need close ups of anything, let me know and I'll get some.

1. Channel B is perfect, the only problem was a crackly EQ pot, but that's sorted now.
2. Reverb didn't seem to make a difference at all, I can't turn it 'off' so to speak, but I've had it turned right down.
3. The only thing I can see with the caps is the green coating on one is cracking and flaking off a little.

Haha, thanks for the schematics, I can spend hours struggling to decipher them

the side of those potentially clipped caps closest to the pots, where they sit on a trace with two diodes? can you check if that trace is ground? Continuity checker between there and say the ground bit on the input jack?

right, next you're gonna have to work on this whilst it's live... be careful but you know the drill, make sure the speaker is attached too or you'll fry the mosfets. I will assume you know which pins are which on an 8 pin chip so I won't explain that either.

You need to measure the voltages of pins 3, 4, 6, 8 on IC1, IC2 and IC3. Do it in reference to ground so make sure your black probe is on a ground connection, then just note them down including if they are 0 or negative (the negatives are important)